(1) Field of the Invention
The present invention relates to a television receiving system, especially relates to an antenna that is capable of switching directivity.
(2) Description of the Related Art
A receiving device is disclosed in Japan patent publication No. 2003-18038. The receiving device uses an antenna to receive television broadcasting signals. Users were adjusting a physical direction of an antenna in order to make a directivity of the antenna optimal for receiving television broadcasting signals by the antenna. However this adjusting method had a problem that this adjusting method was very difficult. So, for example, an antenna system having an indicator indicating a receiving condition of television broadcasting signals in order to manually adjust the physical direction of the antenna existed. Another antenna system that automatically adjusted the physical direction of the antenna upon user's request existed.
Further an antenna (so-called “smart antenna”) that can automatically change the direction of the antenna every time preferable channels are instructed by users is suggested. FIG. 9 is a perspective view of the smart antenna 1. According to this figure, the smart antenna 1 is comprised of an antenna unit 2 with receiving element, a chassis 3 holding the antenna unit 2, shaft portion 4 supporting the chassis 3 at a predetermined height and fixing the chassis 3 to a television receiving device, and a wiring wired from the antenna unit 2 and electrically connected to the television receiving device. According to this configuration, the smart antenna 1 is controlled by the television receiving device based on a predetermined standard through the wiring and changes the directivity.
In case storing the smart antennas that are disused, problems mentioned below are occurred. The smart antennas can be used for compact television receivers because the smart antennas have very high receiving sensitivity and are in compact shapes. The smart antennas detached have to be strictly protected from damages by impacts. Therefore, it is hard to deal with the smart antenna 1 detached from the television receiving device.
In Japan patent publication No. H07-240626A, storing method of antennas that spread comparatively large reflecting surfaces such like parabola antennas. The reflecting surfaces can be divided and folded. Therefore, it is possible to make the parabola antennas compact by folding the reflecting surfaces, when the parabola antennas are stored.
A problem mentioned below occurs in case applying the method disclosed in Japan patent publication No. H07-240626A for the smart antennas. That is, the method is unsuitable for small antennas such like the smart antennas. Further, folding the smart antennas is difficult because chassis of the smart antennas must contain active antenna units.